[otrs] otrs cannot find a file

Hello OTRS, when i access otrs i always got an error wether otrs cannot find a file. But if i checked in server, the files can be found,exacly the same path from error message. EXAMPLE: Backend ERROR: OTRS-CGI-29 Perl: 5.10.1 OS: freebsd Time: Mon Oct 10 12:56:27 2011 Message: Module Kernel/Modules/AdminCustomerUser.pm not found! Traceback (96910): Module: Kernel::System::Web::InterfaceAgent::Run (v1.58) Line: 188 Module: Apache::ROOT::otrs::index_2epl::handler (v1.89) Line: 45 Module: (eval) (v2.01) Line: 149 Module: Apache::Registry::handler (v2.01) Line: 149 what actually the problem is? please help... i'm using freebsd and apache br, toha